Reamers are precision tools for machining existing, or pre-drilled, holes to improve surface quality while, consequently, slightly enlarging the hole. Due to the nature of the precision machining which reamers are designed to carry out, even slight misalignment between the hole and reamer during insertion of the reamer can result in damage to the reamer cutting edges and/or the hole.
Consequently holders called ‘floating reamer holders’ are utilized for holding the reamer. A floating reamer holder is configured to allow, during hole entry, and during reaming, axial misalignment of a reamer axis with respect to the hole axis which, consequently, means that the floating holder reamer enables slight misalignment between the reamer itself (replaceable tool), and the machine that holds and it.
One major disadvantage in tools of the field is that this floating holder reamer adds to the overall overhang, or projection, of the tool from the machine. This can lead to larger bending moment in turning applications due to the tool+holder larger weight.
Some floating reamer holders of the field disclose rather complicated designs with many parts and specifically pins or multiple peripheral protrusions. This has a negative effect on the floating reamer holder's axial length, and obviously on production costs, which usually are directly affected by the number of parts and accurate surfaces that need to be ground.
Floating reamer holders of the field are disclosed, e.g., in U.S. Pat. No. 1,359,103, which discloses a compact, oldham-style floating reamer holder, with holder and reamer portions which transfer torque therebetween via a flat floating member. The floating member is divided into two halves by a virtual plane (in the axial direction). Each half is located in respective female recesses in each of the holder and reamer portions. This “in-line” engagement arrangement between the floating member and the holder and reamer portions exposes the floating member to great shear forces (most transferred torque becomes shear forces applied at said virtual plane), which can lead to wear and early breakage on one hand, and on the other hand, limits machining speeds/productivity.
U.S. Pat. No. 1,566,553 discloses an adjustable floating reamer holder, which enables three types of freedom of movement. However, this arrangement does not provide automatic (i.e., without interference from an operator), accurate centering in a non-operative state. Specifically for enabling angular misalignment, this arrangement includes a ball and coiled spring which are also supposed to center the driven member 20 in a non-operative position (the ball enters centering depressions in the driven and driving members 20, 13). However, the coiled spring alone (abutting the rear end 17 of the driven member 20) only centers the rear end of the driven member 20, leaving the forward end 21 loose and non-centered if the nut 42 is not manually tightened. Therefore, this floating reamer holder would require a recalibration of the driving member with each reamer replacement. Furthermore, the cooperating radial driving lugs/tongues 14 and diametrical slot 9, are exposed to shear forces, resulting from the transferred torque.